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The specific steps of membrane switch inspection
Update:2021-10-09

1. Peel strength test: The peel strength of the glue should not be less than 8N/25mm.

2. Check the size: the allowable range of tolerances not marked on the drawing must comply with the standard, and the rest comply with the drawing regulations.

3. Bubbling detection: equal height, balanced force, flat type: 57~584g force, touch feeling: 170-397g force.


4. Shape comparison: the shape, conductor line, insulation treatment, liner combination, etc. should meet the requirements of the drawings or provide physical samples.

5. Color check: Use visual inspection to compare with the sample or color chart to see if there is any color difference. If the color requirements are particularly strict, use a color difference meter to compare.


6. Hardness test: Use H-grade drawing pen tip to apply 1KG thrust to the line at 45 degrees, and the line must not peel off the conductive ink or produce light transmission.

7. Material inspection: Panels, substrates, silver paste, carbon ink, spacers, adhesives, adhesives, reinforcing plates, and insulation printing should meet the requirements of the drawings.


8. Life test: The number of contact conduction times for each button without shrapnel should be 1 million times, and the number of conduction times with shrapnel and touch-sensing should be 500,000 times.

9. Low temperature test: After the membrane switch is subjected to a low temperature of -10±3°C for 16 hours, it is restored under normal atmospheric conditions for 2 hours, and the water droplets on the surface are wiped off. The resistance value should meet the requirements.

10. Loop resistance test: The resistance value should not be greater than 100Ω. For loops with a total length of more than 150cm and special requirements, loops are separately specified in the drawings, and no break or short circuit is allowed.

11. Insulation resistance test: In a normal temperature and humidity environment, the insulation resistance of the conductor circuit is greater than 500MΩ (500CDC for 1 minute). In normal temperature and humidity tests, the salt spray test should not be less than 20MΩ.

12. High temperature test: After the membrane switch is subjected to a high temperature of 55±2°C for 72 hours, the appearance quality of the membrane switch should be checked in accordance with the requirements of the drawing, and the insulation resistance value measured should be in compliance with the requirements after recovering for 2 hours under normal atmospheric conditions.

13. Salt spray test: The membrane switch is subjected to 5% sodium chloride salt solution, the temperature in the test space is 35±2℃, (connector is sealed) after a 72-hour salt spray test, it is restored under normal atmospheric conditions for 2 hours, The insulation resistance should meet the regulations.

14. Constant damp heat test: the membrane switch is subjected to 40±2℃, relative humidity is 93 (+2%-3%), after 96 hours of constant damp heat test, it is restored under normal atmospheric conditions for 2 hours, and the insulation resistance and circuit are measured. Resistance and pressing force should meet the regulations.

15. Check the appearance: The panel must not have obvious defects, such as characters but strokes, stains, light transmission points, deinking, stains, scratches, transparent window overflow, glue residue, etc., no offset phenomenon, such as printing plates , The combination of upper and lower key positions, circuit and key sheet, panel and key combination, panel key bubbling and substrate, punching burrs and bending size should not be greater than 0.2mm, and the position should be toward the side without conductors.

16. Ink adhesion check: the ink is attached to the transparent tape and pressed by hand to ensure that there are no bubbles and then quickly peeled off after 10 seconds. There should be no ink drop. After the insulating ink is dried, the ink surfaces are pressed against each other and pressed for 24 hours. Make sure that the insulating surfaces do not stick to each other. Use a pressure-sensitive tape to stick it with hand pressure without air bubbles for 1 minute, and peel off quickly without ink shedding.

17. Folding strength test: The circuit resistance of the dried silver paste and carbon ink circuit should be measured first, and then the circuit should be folded 180 degrees, and the finger should be pressed for 2kg/2 seconds, and then it should be restored to the plane , Do it back and forth for 5 times, and then measure its resistance. The resistance increased after 5 times of folding does not exceed 300% of the original resistance.